1. Field of the Invention
The present invention relates to method and apparatus for preparing and transmitting electronic program information multiplexed with video and audio signals. Also, the present invention relates to an apparatus for producing an electronic program guide from the electronic program information multiplexed with the video and audio signals.
2. Description of the Related Art
In digital satellite broadcasting, a video signal and an audio signal are broadcast from a central station to a plurality of terminals according to the Moving Picture Experts Group 2 (MPEG2). In the MPEG2, video and audio signals are multiplexed with each other into a packet in the central station, and a plurality of packets are transmitted to each terminal in the form of a transport stream (TS) representing a transmission line. In this case, electronic program information prescribed in the MPEG2 and DVB is transmitted with the video and audio signals. The electronic program information includes both control information, used to reproduce the video and audio signals multiplexed with each other, and electronic program guide information, used to prepare an electronic program guide. The electronic program guide information is described in a form of a section type table, and the section type is prescribed in MPEG2 and DVB.
2.1. Previously Proposed Art
FIG. 1 shows a configuration of a conventional digital broadcasting system.
As shown in FIG. 1, a conventional digital broadcasting system 300 is composed of a central broadcasting station system 301 and a plurality of viewers' terminals 302. In the central broadcasting station system 301, video and audio signals of television programs are transmitted from a television program and electronic program information organizing system 312 to a video/audio stream producing system 313, and the video and audio signals are prepared as a video/audio stream in the system 313. Also, electronic program scheduling information is transmitted from the television program and electronic program information organizing system 312 to an electronic program information preparing and transmitting system 314, and electronic program information, which is composed of program information, used to reproduce the video and audio signals multiplexed with each other, and added information, used to prepare electronic program information, is prepared in the system 314. The video/audio stream produced in the system 313 and the electronic program information prepared in the system 314 are multiplexed with each other in a TS multiplexer and up-link system 315, the electronic program information multiplexed with the video/audio stream is received in an information receiving device (IRD) 302 at each viewer's terminal (or a television set) through a satellite 316.
Also, cipher key information is transmitted from a cipher key managing and producing system 317 to the IRD 302, and television program viewing information is returned from the IRD 302 to an accounting information collecting system 318 through a public switched telephone network (PSTN) 319.
2.2. Problems to be Solved by the Invention
However, because an electronic program guide (called a common electronic program guide) of television programs provided by all broadcast service providers is prepared in the conventional digital broadcasting system 300 and is displayed in each viewer's terminal 302, an electronic program guide (called an individual electronic program guide) of television programs provided by each broadcast service provider cannot be prepared in the conventional digital broadcasting system 300.
Also, even though each broadcast service provider desires to provide various services for the viewers, because the services provided by one broadcast service provider are set forth in the electronic program guide in the same format as those provided by another broadcast service provider, features of the services provided by each broadcast service provider cannot be realized by the viewer.